THE PEAR LEAF-WORM. 19 
The larva shows no preference for any one part of the leaf. The 
parenchyma and main or lateral ve1ns—even blister-mite galls, when 
these happen to be present—are consumed in turn as met with during 
the continuous circular travel of the larva. A spot of arsenate of 
lead reached in its path of travel becomes part of itsfood. The larva 
does not change its course or eat around it because of a dislike for 
the taste of the poison. 
The larval period occurs at a time when spraying is done for more 
serious pests of the pear. Spraying specifically for its control would 
coincide with the first application of spray for the codling moth, 
when the blossoming period is about over and two-thirds of the petals 
have fallen. The formula of arsenate-of-lead spray used for the 
latter is quite as effective for the pear leaf-worm. 
CALIFORNIA EXPERIMENTS. 
In California, when pear orchards are infested with pear thrips 
(Taeniothrips pyri Daniel), the Government formula of distillate-oil 
emulsion and nicotine! used for the control of the pear thrips larva 
is usually applied at a time when the pear leaf-worms are about all 
hatched, and is also effective, as a contact-spray control, for the 
latter. 
Therefore, in pear orchards well taken care of, when spraying 
for the codling moth has become as much of an indispensable pra:tice 
as that of plowing and cultivating, the pear leaf-worm has less 
chance of becoming a pest of economic importance, and its control can 
be considered as correlative with that of both the codling moth and 
the pear thrips. 
TaBLeE XVI.—California spraying experiments indicating degree of efficiency of different 
formulas against the pear leaf-worm, Apr. 29 and 30, 1913. 
Number of pear leaf-worms. 
Tree sprayed and spray material used. Por Per 
Dead. | Alive. | Sick. cent cent 
dead. | alive. 
Tree No. 1: 
Lead arsenate 4 pounds, water 100 gallons.................- 31 1 2 91 2 
Tree No. 2: 
Lead arsenate 4 pounds, fish-oil soap 10 pounds, 40 per cent 
nicotine sulphate 1/1600, water 100 gallons............... 50 0 0 100 0 
Tree No. 3: 
Fish-oil soap 10 pounds, 40 per cent nicotine sulphate 1/1600, 
Auman eye DUO) fee WUlop aks. ME US AO EE al MeN CII I oe gn 17 15 2 50 44 
Tree No. 4: 
Lead arsenate 4 pounds, fish-oil soap 10 pounds, 40 per cent 
nicotine sulphate 1/1600, water 100 gallons................ 46 5 1 884 93 
Tree No. 5: 
Lead arsenate 4 pounds, fish-oil soap 10 pounds, water 100 
Feaee MUON ONG 5 ye ei as OE a eg a OA RS aA A 38 1 4 
Tree No. 6 i . a _ 
Lead arsenate 6 pounds, water 100 gallons.................. 39 1 0 974 2k 
Tree No. 7: i 
Fish-oil soap 10 pounds, 40 per cent nicotine sulphate 1/1600, 
Water LOO ALTO TS 2 Uy Ne Hn ee St ad WTC nai 16 14 0 53.3 46.6 
1 Foster, S. W., and Jones, P. R. How to Controlthe Pear Thrips. U.S. Dept. Agr. Bur. Ent. Cire. 
131. 24p.,15 fig. 1911. 
